This invention relates to high density memory, and more particularly, to a piezoelectrically actuated ultrananocrystalline diamond tip array integrated with ferroelectric or phase change media.
Electronic memory is useful to input, store and read information, such as data, graphics, videos, etc. Data, graphics, photographs, charts, videos, movies, and internet downloads often require substantial electronic memory. Many stand alone memories and embedded memories for multifunctional electronic devices, such as cell phones with image, video, and voice recording, portable movie systems, computers, and hand held electronic devices and other systems require high-density memories in the gigabit (Gb) to terabit (Tb) range. A gigabit is a unit of information or computer storage, abbreviated Gb. One (1) gigabit=109=1,000,000,000 bits (which is equal to 125 decimal megabytes as 8 bits equals one byte). A terabit is a unit of information or computer storage, abbreviated Tb. One (1) terabit=1012 bits=1,000,000,000,000 bits.
Computer memory and storage refer to computer components, devices and recording media that retain data for some interval of time. Computer storage provides one of the core functions of a computer, that of information retention. Memory often refers to a form of solid state storage known as random access memory (RAM) and sometimes other forms of fast but temporary storage. In computers, for example, the main memory is the electronic solid-state random access memory. Random access means that any location in storage can be accessed at any moment in the same, usually small, amount of time. This makes random access memory well suited for primary storage. RAM is directly connected to the central processing unit memory bus and a data bus. RAM can very quickly transfer information between a processor register and locations in main storage, also known as a memory addresses. The memory bus is also called an address bus or front side bus and both busses are high-speed digital superhighways. Access methods and speed are two of the fundamental technical differences between memory and mass storage devices.
Memory can be split into two main categories: volatile and nonvolatile. Volatile memory loses data as soon as the system is turned off and requires constant power to remain viable. Most types of random access memory (RAM) fall into this category. Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. Since real capacitors leak charge, the information eventually fades unless the capacitor charge is refreshed periodically. Since DRAM loses its data when the power supply is removed, it is in the class of volatile memory devices.
Non-volatile memory will retain the stored information even if it is not constantly supplied with electric power. It is suitable for long-term storage of information. Examples of non-volatile memory include read-only memory, flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy disk drives, and magnetic tape), optical disc drives, and the new generation of non-volatile ferroelectric random access memories, now in the market in “smart cards” and RFID devices, and the upcoming phase change memories. Storage often refers to mass storage—optical discs, forms of magnetic storage like hard disks, and other types of storage which are slower than RAM, but of a more permanent nature. Off-line storage is used for data transfer and archival purposes. In computers, compact discs, DVDs, memory cards, flash memory devices including USB drives, floppy disks, Zip disks and magnetic tapes are commonly used for off-line mass storage purposes.
Flash memory is a form of non-volatile computer memory that can be electrically erased and reprogrammed. Flash memory is relatively inexpensive and can be useful wherever a significant amount of non-volatile, solid-state storage is needed. Memory cards primarily use flash memory. Compact flash (CF) was originally developed as a type of data storage device used in portable electronic devices. Flash memory devices are non-volatile and solid state. CF devices are used in handheld and laptop computers digital cameras, and a wide variety of other devices, including portable audio recorders and desktop computers. The only difference between CF Type I and CF Type II cards is the card thickness. Compact flash cards are designed with flash technology and provide a nonvolatile storage that does not require a battery to retain data indefinitely.
Flash memory is also used in universal serial bus (USB) flash drives and can be used for general storage and transfer of data between computers. USB flash drives are NAND-type flash memory data storage devices integrated with a universal serial bus (USB) interface. USB flash drives are small, lightweight, removable and rewritable. USB flash drives presently have memory capacities from 32 megabytes up to 64 gigabytes. USB flash drives are more compact, generally faster, hold more data, and are more reliable, due to both their lack of moving parts, and their more durable design, than floppy disks. A flash drive consists of a small printed circuit board encased in a plastic or metal casing, making the drive sturdy enough to be carried about in a pocket, as a key fob, or on a lanyard. Only the USB connector protrudes from this protection, and is usually covered by a removable cap. Most flash drives use a standard type-A USB connection allowing them to be connected directly to a port on a personal computer. To access the data stored in a flash drive, the drive must be connected to a computer, either by plugging it into a USB host controller built into the computer, or into a USB hub. Flash drives are active only when plugged into a USB connection and draw all necessary power from the supply provided by that connection. There typical parts of a flash drive are: (1) Male type-A USB connector that provides an interface to the host computer; (2) USB mass storage controller that implements the USB host controller and provides a linear interface as well as contains a small RISC microprocessor and a small amount of on-chip ROM and RAM; (3) NAND flash memory chip that stores data; and (4) crystal oscillator that produces the flash drive's clock signal and controls the device's data output through a phase-locked loop. Flash drives are also a relatively dense form of storage, where even the cheapest will store dozens of floppy disks worth of data.
Significantly, the memory density of flash memory in compact flash (CF) memory cards and USB flash drives, limits its capacity and performance. Furthermore, flash memory devices, such as compact flash (CF) memory cards and USB flash drives can sustain only a limited number of write and erase cycles before failure.
It is, therefore, desirable to provide a storage device with high-density memory, which overcomes most, if not all of the preceding disadvantages.